1. Field of the Invention
The present invention generally relates to contouring, sanding and polishing spherical surfaces, and more particularly, is concerned with a tool assembly for finishing, that is, sanding and polishing, a bowling ball surface.
2. Description of the Prior Art
On occasion, bowling balls must be refinished by sanding and polishing the outer spherical surface. Oftentimes refinishing is necessary when a bowling ball has changed ownership and the ball's finger holes have been plugged with filler material so that they may be redrilled to match the hand and finger size of the new owner. In these cases the excess plug material must be abraded down to match the bowling ball's original spherical surface. Special care must be taken not to compromise the sphericity of the ball. If the ball is out-of-round its usefulness at the bowling alley will be diminished. Easy to use and inexpensive tools are required so that a person of average technical skill can successfully refinish a bowling ball without sacrificing the ball's sphericity.
One commonly used method for refinishing bowling balls is to use hand-held sand paper which is abraded against the ball in the areas which require attention. Polishing is performed by placing polishing compounds on a rag and rubbing the bowling ball. This operation can be simplified and performed more quickly by placing the bowling ball on a machine which rotates the ball while the sandpaper or polishing rag is introduced to the ball. There are several problems with this method. Uneven hand pressure will decrease the sphericity of the ball. This problem is particularly apparent around plugged finger holes where sanding may be concentrated. Another problem has to do with skin contact with the rubbing compounds which may cause skin irritation. Sanding is sometimes done in water, and skin irritation may result from the mixture of abrasive debris and water.
A more advanced method involves creating a rigid concave pattern of an area of the bowling ball which is to be refinished. To do this, cellophane wrap is placed around the ball and a clay ring dam is built on the cellophane. The dam should enclose an area the size of the rigid concave pattern desired. The dam is then filled with finger hole filler material which is left to harden. After hardening, the rigid filler material pattern is removed from the cellophane. Sandpaper is then placed in the formed spherical depression and the assembly is abraded against the bowling ball. -This device may also be used in conjunction with a ball spinner which will hasten the abrasion process. Using this rigid concave pattern, the ball may be more evenly sanded than if the sandpaper was held by hand, however this method has several drawbacks. First, it is difficult to keep the sandpaper fixed in the spherical depression. Also, the sandpaper tends to wrinkle, decreasing the ball contact area. Furthermore, the pattern is rigid, and therefore does not mate well with all bowling balls, so a new pattern is required for each ball refinished. Finally, the practical size for these patterns is fairly small, thereby limiting the contact area between the sandpaper and the ball.
Mechanical apparatuses designed for grinding and polishing spherical balls are described in U.S. Pat. No. 3,024,578 to Mushkin and U.S. Pat. No. 3,961,448 to Akahane. The Mushkin device is for grinding the exterior surfaces of spherical balls, especially bowling balls, from rough spherical castings. Two grinding heads, with abrasive conical interior elements into which the ball rests, are angularly disposed on the supporting framework. One grinding head rotates and the other is rotationally stationary, but forced against the ball to keep constant contact. The Akahane apparatus is a polishing device for finishing spheres of hard materials, or production of concave or convex lenses. Three polishing dishes are fixed at the end of three drive shafts which are in the same plane and 120 degrees apart. The rough ball is placed such that all three polishing dishes contact. The dishes rotate, thereby polishing the ball. Both of these apparatuses are designed more for production purposes than for use by the average sportsperson wishing to refinish a bowling ball. Furthermore, these apparatuses are relatively complicated and, if commercially available, would likely require a substantial investment.
Consequently, a need exists for a bowling ball finishing device which is affordable, simple to use and gives consistent and reliable results on any bowling ball without sacrificing sphericity.